package org.apache.maven.plugin;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.maven.artifact.Artifact;
import org.apache.maven.model.Plugin;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
import org.codehaus.plexus.component.annotations.Component;
import org.codehaus.plexus.personality.plexus.lifecycle.phase.Disposable;
import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.graph.DependencyFilter;
import org.eclipse.aether.repository.LocalRepository;
import org.eclipse.aether.repository.RemoteRepository;
import org.eclipse.aether.repository.WorkspaceRepository;

/**
 * Default PluginCache implementation. Assumes cached data does not change.
 */
@Component(role = PluginRealmCache.class)
public class DefaultPluginRealmCache implements PluginRealmCache, Disposable {

  protected static class CacheKey implements Key {

    private final Plugin plugin;

    private final WorkspaceRepository workspace;

    private final LocalRepository localRepo;

    private final List<RemoteRepository> repositories;

    private final ClassLoader parentRealm;

    private final Map<String, ClassLoader> foreignImports;

    private final DependencyFilter filter;

    private final int hashCode;

    public CacheKey(Plugin plugin, ClassLoader parentRealm, Map<String, ClassLoader> foreignImports, DependencyFilter dependencyFilter, List<RemoteRepository> repositories, RepositorySystemSession session) {
      this.plugin = plugin.clone();
      this.workspace = CacheUtils.getWorkspace(session);
      this.localRepo = session.getLocalRepository();
      this.repositories = new ArrayList<RemoteRepository>(repositories.size());
      for (RemoteRepository repository : repositories) {
        if (repository.isRepositoryManager()) {
          this.repositories.addAll(repository.getMirroredRepositories());
        } else {
          this.repositories.add(repository);
        }
      }
      this.parentRealm = parentRealm;
      this.foreignImports = (foreignImports != null) ? foreignImports : Collections.<String, ClassLoader> emptyMap();
      this.filter = dependencyFilter;

      int hash = 17;
      hash = hash * 31 + CacheUtils.pluginHashCode(plugin);
      hash = hash * 31 + hash(workspace);
      hash = hash * 31 + hash(localRepo);
      hash = hash * 31 + CacheUtils.repositoriesHashCode(repositories);
      hash = hash * 31 + hash(parentRealm);
      hash = hash * 31 + this.foreignImports.hashCode();
      hash = hash * 31 + hash(dependencyFilter);
      this.hashCode = hash;
    }

    @Override
    public String toString() {
      return plugin.getId();
    }

    @Override
    public int hashCode() {
      return hashCode;
    }

    private static int hash(Object obj) {
      return obj != null ? obj.hashCode() : 0;
    }

    @Override
    public boolean equals(Object o) {
      if (o == this) {
        return true;
      }

      if (!(o instanceof CacheKey)) {
        return false;
      }

      CacheKey that = (CacheKey) o;

      return parentRealm == that.parentRealm && CacheUtils.pluginEquals(plugin, that.plugin)
          && eq(workspace, that.workspace) && eq(localRepo, that.localRepo)
          && CacheUtils.repositoriesEquals(this.repositories, that.repositories) && eq(filter, that.filter)
          && eq(foreignImports, that.foreignImports);
    }

    private static <T> boolean eq(T s1, T s2) {
      return s1 != null ? s1.equals(s2) : s2 == null;
    }

  }

  protected final Map<Key, CacheRecord> cache = new ConcurrentHashMap<Key, CacheRecord>();

  public Key createKey(Plugin plugin, ClassLoader parentRealm, Map<String, ClassLoader> foreignImports,
      DependencyFilter dependencyFilter, List<RemoteRepository> repositories, RepositorySystemSession session) {
    return new CacheKey(plugin, parentRealm, foreignImports, dependencyFilter, repositories, session);
  }

  public CacheRecord get(Key key) {
    return cache.get(key);
  }

  public CacheRecord put(Key key, ClassRealm pluginRealm, List<Artifact> pluginArtifacts) {
    if (pluginRealm == null || pluginArtifacts == null) {
      throw new IllegalArgumentException();
    }

    if (cache.containsKey(key)) {
      throw new IllegalStateException("Duplicate plugin realm for plugin " + key);
    }

    CacheRecord record = new CacheRecord(pluginRealm, pluginArtifacts);

    cache.put(key, record);

    return record;
  }

  public void flush() {
    for (CacheRecord record : cache.values()) {
      ClassRealm realm = record.realm;
      try {
        realm.getWorld().disposeRealm(realm.getId());
      } catch (NoSuchRealmException e) {
        // ignore
      }
    }
    cache.clear();
  }

  protected static int pluginHashCode(Plugin plugin) {
    return CacheUtils.pluginHashCode(plugin);
  }

  protected static boolean pluginEquals(Plugin a, Plugin b) {
    return CacheUtils.pluginEquals(a, b);
  }

  public void register(MavenProject project, CacheRecord record) {
    // default cache does not track plugin usage
  }

  public void dispose() {
    flush();
  }

}
